Immunosorbents Coupled On-Line with Liquid Chromatography/Atmospheric Pressure Chemical Ionization/Mass Spectrometry for the Part per Trillion Level Determination of Pesticides in Sediments and Natural Waters Using Low Preconcentration Volumes

Abstract

A new automated on-line immunosorbent phase extraction method was developed and validated for the analysis of triazine and phenylurea herbicides in environmental matrixes such as sediments and natural waters. This method is a first application and consists of trace analyte extraction using an immunosorbent column containing either anti-atrazine or anti-chlortoluron antibodies combined with a liquid chromatograph by use of an on-line sample preparation system coupled directly to an atmospheric pressure chemical ionization/mass spectrometer in positive mode of operation. After the percolation of 20 mL of water through the immunosorbent columns, high recoveries of extraction were obtained for all the compounds with the exception of deisopropylatrazine and diflubenzuron. Calibration curves were linear in the range between 0.01 and 0.2 μg/L in groundwater. The limits of detection ranged from 0.001 to 0.005 μg/L, indicating good sensitivity achieved by both types of immunosorbents. Environmental sediment samples from the Ebre Delta area (Tarragona, Spain) containing several triazines and linuron were Soxhlet extracted with methanol, and the extracts were brought to a volume of 100 mL in water in order to perform the extraction with the immunosorbents. No significant interferences from the sample matrix were noticed, thus indicating a good selectivity of the immunosorbents used. Seawater samples from a marina nearby (Masnou, Barcelona, Spain) were also analyzed. An interlaboratory study using Aquacheck-certified groundwater samples was carried out in order to validate the application of the method for the analysis of environmental samples.